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Would injector swap cause failed e test?

Old 10-17-2015, 12:19 PM
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Default Would injector swap cause failed e test?

Quick background.
88 Jeep XJ

I did the ground refresh and C101 connector removal.

I also did the injector swap to the ones a Dodge Neon uses.

It failed the emision test for the first time in the 15 years I have had it. It did not fail the prior emission test when it had the stock injectors on it.

Here is what the test results are.

HC 6.3547 limit 3.00
CO 167.4258 limit 25.00
CO2. 420.9423 no limit stated
NOx 1.5559 limit 5.000

Question I have is would the injector swap cause it to run rich like it is?

Any help would be great.
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Old 10-17-2015, 12:37 PM
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Did you go through cruised54's renix tips and check all of them out where it comes to injectors?
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Old 10-17-2015, 03:22 PM
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Assuming those are 703's, the ECU should be able to adjust the trim within specs. They DO have a slightly higher flow rate which only might matter when the puter is running on default settings in "open loop" Plenty of renix Jeeps have passed with 703's......
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Old 10-17-2015, 06:38 PM
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With high HC and CO, you are definitely running rich. I have 703's in my Renix XJ with no issues.
When was the last time you tested and/or replaced your O2 sensor? Tune-up, cooling system flush? Make sure to test your CTS and IAT sensors as well. lunghd site has specs and how to test.

Maybe evem run some Seafoam, MMO etc through fuel system.
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Old 10-18-2015, 11:21 AM
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So I tweaked a bit more things to get a better ground.

The first reading on port B of the TPS and the ground of the battery was at about 5 ohms. I wiggled the harness around and suddenly it spiked all the way to 13 ohms and stayed there.
I tried to pin point it a bit more and discovered when I wiggled that grey plug right on the firewall with 5 leads going into it would change the ohm reading drastically.
So I cleaned it up and the ohms dropped to .2 to .3 at the TPS. Much better.

I then replaced the TPS with a new one I had that I never got around to installing. The old one would stick every so often on really cold days.

Now it seems to run a tiny bit smother when applying the throttle.

Lastly I replaced the ground braided wire going from the firewall to the engine head.

Also an additional note, I did replace the distributor, cap, rotor, wires and plugs including the coil earlier this summer. The engine does not burn any oil either.

It still does have a definite smell of running rich though.

I'll check the Air temp sensor and O2 sensor next now that I have a good ground.

Also as an additional note, I did replace the distributor, cap, rotor, wires and plugs including the coil earlier this summer. The engine does not burn any oil either.

Last edited by 88Dutchman; 10-18-2015 at 11:28 AM.
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Old 10-18-2015, 12:04 PM
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Just realized something else. Being we are in the hills here in Colorado, many times the engine would almost go nuclear going up long up hill mountain passes.
I installed a lower temp water thermostat that would keep the coolant to about 180ish degrees in the mountains and it's worked great. BTW I did upgrade the cooling system to a 95 and newer too.

However, in around town and highway driving the temp gauge says the temp is hardly beyond 100 degree mark.

I thought that it was a 160 degree that I installed but now I'm not too sure.

Anyway, is it possible that the engine is running rich because it thinks it's still not warmed up?
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Old 10-18-2015, 01:14 PM
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Allot of us run the Mopar 195* T-Stat. It, like cooler ones will be fully open before any overheat. I gathered 160* is the minimum you might expect to to function ...OK. I'd expect at least a little more complete fuel burning at normal running temp though. HC's are just un-burnt fuel. That MAP tube is crucial btw...

Last edited by DFlintstone; 10-18-2015 at 01:23 PM.
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Old 10-18-2015, 04:52 PM
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Have you indexed your dizzy, via instructions from Cruiser's tips?
WHat was your source for the injectors? As I already stated, run some kind of good fuel system cleaner through. And, you need to ditch that stat for OE temp. The lower operating temp is not helping your A/F ratio at all.

Last edited by Metmknice; 10-18-2015 at 04:55 PM.
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Old 10-27-2015, 10:36 PM
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Well, second test results were better but....it still did not pass by just the slightest margin.

New results are
HC. 1.2342 Was 6.3547 max 3.00
CO. 18.0887 was 167.4258 max 25.00
Nox 5.452 was. 1.5550. max 5.00

I did get some faulty ground issues straightend out.
The O2 sensor had a much higher ohm reading than its supposed to so I replaced it as well.

Fyi, the Catelytic converter is only two years old.
Also I did run some seafoam through the intake and fuel tank.

Yes I did setup the dizzy as per Cruisers tip when I got a new one.

Last edited by 88Dutchman; 10-27-2015 at 10:44 PM.
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